(6-Diphenylphosphinoacenaphth-5-yl)indium and -nickel Compounds: Synthesis, Structure, Transmetalation, and Cross-Coupling Reactions

The reaction of (5-Ph₂P-Ace-6-)Li (I) with InCl₃ provided (6-Ph₂P-Ace-5-)₃In (1), which proved to be a remarkably mild transmetalation reagent. The reaction of 1 with NiCl₂, originally aimed to allow for a Z-type complex, gave (6-Ph₂P-Ace-5-)₂InCl (2) and (6-Ph₂P-Ace-5-)₂Ni (3), a rare example of a well-defined σ-bonded diorganonickel species. The reaction of (6-Ph₂P-Ace-5-)­X (II, X = F; III, X = Cl; IV, X = Br; V, X = I) with Ni­(COD)₂ gave rise to the related dinuclear organonickel halides [(6-Ph₂P-Ace-5-)­NiX]₂ (4, X = F; 5, X = Cl; 6, X = Br; 7, X = I), which upon addition of MeCN yielded the mononuclear complexes (6-Ph₂P-Ace-5-)­Ni­(NCMe)­X (8, X = Cl; 9, X = Br; 10, X = I). At slightly elevated temperatures, 3–7 undergo a C–C cross-coupling reaction to give 6,6′-bis­(diphenylphosphino)-5,5′-biacenaphthyl, (6-Ph₂P-Ace-5-)₂ (11), having the potential for axial chirality. The electronic structures of 1–10 were investigated by DFT and TD-DFT calculations, including a set of real-space bonding indicators derived from the atoms in molecules (AIM), electron localizability indicator (ELI), and noncovalent interaction (NCI) index schemes.